scan_shadow_nodes() is the only user of __list_lru_walk_one() which
disables interrupts before invoking it. The reason is that nlru->lock is
nesting inside IRQ-safe i_pages lock. Some functions unconditionally
acquire the lock with the _irq() suffix.
__list_lru_walk_one() can't acquire the lock unconditionally with _irq()
suffix because it might invoke a callback which unlocks the nlru->lock
and invokes a sleeping function without enabling interrupts.
Add an argument to __list_lru_init() which identifies wheather the
nlru->lock needs to be acquired with disabling interrupts or without.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
include/linux/list_lru.h | 12 ++++++++----
mm/list_lru.c | 14 ++++++++++----
mm/workingset.c | 12 ++++--------
3 files changed, 22 insertions(+), 16 deletions(-)
diff --git a/include/linux/list_lru.h b/include/linux/list_lru.h
index 96def9d15b1b..c2161c3a1809 100644
--- a/include/linux/list_lru.h
+++ b/include/linux/list_lru.h
@@ -51,18 +51,22 @@ struct list_lru_node {
struct list_lru {
struct list_lru_node *node;
+ bool lock_irq;
#if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
struct list_head list;
#endif
};
void list_lru_destroy(struct list_lru *lru);
-int __list_lru_init(struct list_lru *lru, bool memcg_aware,
+int __list_lru_init(struct list_lru *lru, bool memcg_aware, bool lock_irq,
struct lock_class_key *key);
-#define list_lru_init(lru) __list_lru_init((lru), false, NULL)
-#define list_lru_init_key(lru, key) __list_lru_init((lru), false, (key))
-#define list_lru_init_memcg(lru) __list_lru_init((lru), true, NULL)
+#define list_lru_init(lru) __list_lru_init((lru), false, false, \
+ NULL)
+#define list_lru_init_key(lru, key) __list_lru_init((lru), false, false, \
+ (key))
+#define list_lru_init_memcg(lru) __list_lru_init((lru), true, false, \
+ NULL)
int memcg_update_all_list_lrus(int num_memcgs);
void memcg_drain_all_list_lrus(int src_idx, int dst_idx);
diff --git a/mm/list_lru.c b/mm/list_lru.c
index fcfb6c89ed47..1c49d48078e4 100644
--- a/mm/list_lru.c
+++ b/mm/list_lru.c
@@ -204,7 +204,10 @@ __list_lru_walk_one(struct list_lru *lru, int nid, int memcg_idx,
struct list_head *item, *n;
unsigned long isolated = 0;
- spin_lock(&nlru->lock);
+ if (lru->lock_irq)
+ spin_lock_irq(&nlru->lock);
+ else
+ spin_lock(&nlru->lock);
l = list_lru_from_memcg_idx(nlru, memcg_idx);
restart:
list_for_each_safe(item, n, &l->list) {
@@ -251,7 +254,10 @@ __list_lru_walk_one(struct list_lru *lru, int nid, int memcg_idx,
}
}
- spin_unlock(&nlru->lock);
+ if (lru->lock_irq)
+ spin_unlock_irq(&nlru->lock);
+ else
+ spin_unlock(&nlru->lock);
return isolated;
}
@@ -553,7 +559,7 @@ static void memcg_destroy_list_lru(struct list_lru *lru)
}
#endif /* CONFIG_MEMCG && !CONFIG_SLOB */
-int __list_lru_init(struct list_lru *lru, bool memcg_aware,
+int __list_lru_init(struct list_lru *lru, bool memcg_aware, bool lock_irq,
struct lock_class_key *key)
{
int i;
@@ -580,7 +586,7 @@ int __list_lru_init(struct list_lru *lru, bool memcg_aware,
lru->node = NULL;
goto out;
}
-
+ lru->lock_irq = lock_irq;
list_lru_register(lru);
out:
memcg_put_cache_ids();
diff --git a/mm/workingset.c b/mm/workingset.c
index 529480c21f93..23ce00f48212 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -480,13 +480,8 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
static unsigned long scan_shadow_nodes(struct shrinker *shrinker,
struct shrink_control *sc)
{
- unsigned long ret;
-
- /* list_lru lock nests inside the IRQ-safe i_pages lock */
- local_irq_disable();
- ret = list_lru_shrink_walk(&shadow_nodes, sc, shadow_lru_isolate, NULL);
- local_irq_enable();
- return ret;
+ return list_lru_shrink_walk(&shadow_nodes, sc, shadow_lru_isolate,
+ NULL);
}
static struct shrinker workingset_shadow_shrinker = {
@@ -523,7 +518,8 @@ static int __init workingset_init(void)
pr_info("workingset: timestamp_bits=%d max_order=%d bucket_order=%u\n",
timestamp_bits, max_order, bucket_order);
- ret = __list_lru_init(&shadow_nodes, true, &shadow_nodes_key);
+ /* list_lru lock nests inside the IRQ-safe i_pages lock */
+ ret = __list_lru_init(&shadow_nodes, true, true, &shadow_nodes_key);
if (ret)
goto err;
ret = register_shrinker(&workingset_shadow_shrinker);
--
2.18.0
